Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Condensed Statements of Cash Flows (Details) - USD ($) $ in Millions		12 Months Ended
	Feb. 26, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net cash flows provided by operating activities		$ 8,445	$ 7,616	$ 4,457
Cash flows from investing activities
Proceeds From Lease Termination	$ 335	360
Proceeds from Sale and Collection of Lease Receivables		360	0	335
Capital expenditures		(8,553)	(7,624)	(6,077)
Cash and restricted cash acquired from Constellation		0	0	140
Change in restricted cash		(42)	66	(104)
Other investing activities		(153)	(119)	(88)
Net cash flows used in investing activities		(15,503)	(7,822)	(4,599)
Cash flows from financing activities
Changes in short-term borrowings		240	0	0
Issuance of long-term debt		4,716	6,709	3,463
Retirement of long-term debt		(1,936)	(2,687)	(1,545)
Proceeds from Issuance of Common Stock		0	1,868	0
Dividends paid on common stock		(1,166)	(1,105)	(1,065)
Proceeds from employee stock plans		55	32	35
Other financing activities		(85)	(99)	(178)
Net cash flows provided by financing activities		1,191	4,830	411
(Decrease) Increase in cash and cash equivalents		(5,867)	4,624	269
Cash and cash equivalents at beginning of period		6,502	1,878	1,609
Cash and cash equivalents at end of period		635	6,502	1,878
Exelon Corporate [Member]
Net cash flows provided by operating activities		1,029	3,071	806
Cash flows from investing activities
Payments to Acquire Businesses, Net of Cash Acquired		(6,962)
Proceeds from Sale and Collection of Lease Receivables		0	0	335
Increase (Decrease) Due from Affiliates		1,390	(1,217)	(83)
Increase (Decrease) in Due from Affiliates, Current		0	550	0
Capital expenditures		0	0	1
Investment in affiliates		(1,757)	(212)	(70)
Other investing activities		5	(55)	(126)
Net cash flows used in investing activities		(7,324)	(934)	57
Cash flows from financing activities
Issuance of long-term debt		1,800	4,200	1,150
Retirement of long-term debt		(46)	(2,263)	(23)
Proceeds from Issuance of Common Stock		0	1,868	0
Dividends paid on common stock		(1,166)	(1,105)	(1,065)
Proceeds from employee stock plans		55	32	35
Other financing activities		(20)	(58)	(84)
Net cash flows provided by financing activities		623	2,674	13
(Decrease) Increase in cash and cash equivalents		(5,672)	4,811	876
Cash and cash equivalents at beginning of period		5,690	879	3
Cash and cash equivalents at end of period		$ 18	$ 5,690	$ 879